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Well start this chapter by admitting our bias. Were impressed with Extrude, but our regard for it is a mix of awe and loathing. Extrude is very powerful and, when used wisely, allows even the artistically inept to produce impressive art. But we draw a sharp distinction between artistic ineptitudeas in incapable of drawing straight lines and round circlesand aesthetic insensitivityas in incapable of recognizing good art from bad art. If what you lack is good taste rather than good skills, Extrude will only help you dig a deeper grave for yourself. On that cautionary note, we invite you into this chapter. Faking Out RealityOur bias notwithstanding, adding an extrusion to an object stands as one of DRAWs most clever functions. With Extrude, you can select any simple object and instantly turn it into something three-dimensional, as either a perspective drawing or an isometric drawing. To produce a 3D appearance, Extrude creates new surfaces that are dynamically linked to the original object. It does this by projecting the edges and corners of the object and then connecting those points to form closed surfaces. Like all of the other depth-defying effects in DRAW, this one is a fake, but its a darn good one. To create an extrusion, do this:
To be a candidate for extrusion, you must be a single object, not a group. You can be a multipathed object and you can be text. But you cant be multiple objects selected or grouped. Text that is extruded is still editable, and the extrusion will update automatically to reflect the edits. Similarly, other control objects can be stretched, skewed, rotated, and so forth, and the extrusion will be updated following the changes.
Perspective vs. IsometricFigure 15.1 shows the difference between a perspective drawing and an isometric illustration. Perspective drawings reflect the fact that objects appear to get smaller the farther they get from the viewer; in that respect, they more closely mimic reality. Isometric drawings do not recede, and therefore they are useful for technical drawings, where a viewer can make accurate length measurements parallel to any axis. DRAW refers to an isometric extrusion as a parallel extrusion.
Controlling an ExtrusionAs with the other effects, Extrude has its own property bar, which comes alive anytime you select an extruded object or reach for the Extrude tool. Figure 15.2 shows the various controls that relate to the extrusion, some of which youll reach for regularly, and some about which you will never have a clue nor will care to.
For the following section, we created a very simple extrusion to act as our laboratory animal:
Well turn our donut loose on the more prominent components of Extrude. To learn about all of them, consult DRAWs online Help: search for extrusions in the index.
Extrusion TypeThere are four perspective choices and two isometric choices. In all cases, the distinction arises in the direction of the extrusion. In the following graphics, we have included a simple light source, to help you observe depth. Small Back This is the defaultmost users want to create 3D objects that recede into the distance. The lines of this type of an extrusion move away from you and grow smaller as they do. Small Front This extrusion sends the object toward you. As it is now receding and growing bigger at the same time, your eyes wont believe that the object has a single circumference. It makes the object look more like a cone. Big Back This produces the same effect as Small Front, except the back side is expanded, rather than the front side reduced. Therefore, the entire object is larger. Big Front This is the same as Small Back, except the resulting object is larger. Back Parallel (Isometric) The lines of this extrusion move away from your line of sight, but they do not recede; they remain the same size. This does not reflect reality, but it makes it easier to determine object dimension. Does the back of this extrusion look bigger than the front? It does to us, even though its not. We think this is because we are accustomed to seeing it as much smaller as it recedes; when it doesnt recede, it appears big.
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